Tuberculosis (“TB”) is a bacterial infection caused by members of the TB complex. Transmission occurs when a person with active pulmonary TB coughs, sneezes or spits, releasing a contaminated aerosol into the air. Inhalation of the released bacteria is the most common mode of infection. Highly infectious individuals are capable of transmitting the disease to 10 to 15 persons a year. While approximately one third of the world's population is infected with TB bacteria, the majority are asymptomatic latent TB infections (“LTBI”). Of the LTBI cases, one in ten will progress to active TB infection which, left untreated, have a 50% mortality rate. Persons lacking a competent immune system (i.e., children) or who are immuno-compromised (i.e., substance abuse, immunosuppresive drugs, HIV/AIDS, diabetes, kidney failure, etc.) are most at risk.
The World Health Organization declared TB a global health emergency in 1993. With close to 9 million new cases and 2 million TB-related deaths each year, this emergency is fueled by HIV and the growing threat of multi-drug resistant (“MDR-TB”). There are nearly 300,000 new cases of MDR-TB each year and over 50 million people are latently infected with MDR strains of TB. Persons co-infected with HIV and TB are most susceptible to active TB disease. It is recognized that the key to controlling the spread of TB is rapid and accurate diagnosis. TB diagnostics can be used not only in the diagnosis of symptomatic patients, but also in therapeutic drug monitoring. Thus, a need exists for a sensitive assay that is specific for the TB complex organisms, and which minimizes the potential for forming potentially contaminating aerosols that put technologists at risk.